In recent years, in a dialysis apparatus as a blood purification apparatus, a technology has been proposed in which priming, returning blood and substitution (emergency infusion) are performed by using a dialysate to be supplied to a dialyzer during dialysis treatment (in particular, online HDF or online HF), or a technology has been proposed in which the dialysate is used as a substitution solution for the online HDF or the online HF. For example, PTL 1 discloses a dialysis apparatus including a substitution line where one end is connected to a dialysate extraction port (collection port) formed in a predetermined section of a dialysate introduction line and the other end is connected to a blood circuit (artery side blood circuit or vein side blood circuit); and a substitution pump which is arranged in the substitution line. In order for such a dialysis apparatus to perform the priming, the returning blood or the substitution (emergency infusion), the substitution pump is driven to supply the dialysate in the dialysate introduction line to the blood circuit (artery side blood circuit or vein side blood circuit).
In general, a cap (on-off device) is attachable to and detachable from the dialysate extraction port, and the substitution line is connected by detaching the cap and when the substitution line is not connected, the dialysate flowing in the dialysate introduction line is not caused to leak out by attaching the cap. For example, in order to clean and disinfect a pipe for circulating the dialysate, such as the dialysate introduction line and the dialysate discharge line, cleaning water or disinfecting solution is circulated in the pipe in a state where the cap is attached to the collection port. In this manner, the cleaning water or the disinfecting solution is prevented from leaking out.
Thus, if the cap comes into close contact with and seals an inner peripheral surface of the collection port, the cleaning water or the disinfecting solution cannot be circulated with respect to the sealed portion, thereby creating a possibility that the cleaning and the disinfecting may be insufficiently performed. Therefore, in the related art, in order that the cap seals an outer peripheral surface of the collection port, a configuration has been proposed where the cleaning water or the disinfecting solution can reach the inner peripheral surface of the collection port (for example, refer to PTL 2 and PTL 3). Thus, if a flow route is extended to circulate the cleaning water or the disinfecting solution from the cap, the cleaning water or the disinfecting solution is circulated inside the collection port, thereby enabling the cleaning and the disinfecting to be sufficiently performed. Some examples may be found in PTL 1: Japanese Unexamined Patent Application Publication No. 2004-313522; PTL 2: Japanese Unexamined Patent Application Publication No. 2003-93501; and PTL 3: Japanese Unexamined Patent Application Publication No. 2009-207706 all of which are expressly incorporated by reference herein for all purposes.